536 F. V. EMERSON 
load to the Louisiana region. Furthermore, such a river in flood 
would necessarily back up the tributaries and loessial materials 
would be deposited along the tributaries in contrast with the actual 
fairly straight margin where it crosses a tributary. 
So far as the structure of the loess is concerned, it might have 
accumulated in lakes or have been deposited by winds, but in the 
hundreds of miles of loess belts below Cairo there are no restrain- 
ing barriers which would impound lakes. Moreover, lakes in which 
10 to 50 feet of loess accumulated must have existed long enough 
for deltas to have been built and shore lines developed, for in such 
temporary lakes as the Red River raft lakes of Louisiana one may 
find well-developed shore lines around these nearly drained lakes. 
No such shore lines have been seen in the Louisiana loess areas and 
none to the writer’s knowledge have been reported elsewhere in the 
Lower Mississippi Basin. 
The relations of the loess to the underlying buried Lafayette- 
Columbia sandy hills near the Mississippi strongly suggest an 
eolian origin (Fig. 1). The absence of truncation of these buried 
hilltops, the very faint or frequent absence of interstratification of 
loess and sand at the contact, all point to a weak depositing agent 
such as wind. The greater thickness of loess near the Mississippi 
is not inconsistent with an eolian origin, for the dust-laden winds 
blowing from the lowlands to the uplands would have their velocity 
checked and so drop part of their load near the river. The work 
of Shimek shows that the loess fossils in this region, mostly snails, 
belong to a land fauna, there being “no species which are aquatic 
or even semi-aquatic,’’’ and the virtual absence of a water fauna 
is equally significant. 
DIRECTIONS OF LOESS-BEARING WINDS 
Assuming the eolian theory of loess in Louisiana, there are three 
lines of evidence available as to the directions of loess-depositing 
winds, namely: (1) the width and thickness of the loess belts on 
either side of the Mississippi, (2) the composition of the loess, and 
(3) the thickness of loess on some isolated areas which were ex- 
posed to the sweep of winds from many directions. 
1 Am. Geologist, XXX, 282. 
